YOU buy a used car with a lot of miles on it and a history of strong performance, save for recent breakdowns. You see enough potential in it and you believe enough in the repairs made on it to think it can perform close to the way it did in its prime. You plunk down $10,000 and take your chances.

Then you take it home and every time you start it up, it backfires. It breaks down often and causes you to miss appointments. The car is hurting your life. You try to trade it in but no lot wants it.

You have the option of ditching it and buying a reliable one, though not as fancy, not as big a name, with no history of outstanding performance. The good news is you can have it for $200.

What do you do?

Obviously, you junk the $10,000 car because you’re tired of looking at your mistake. You decide you aren’t going to let it hurt you twice, once in the wallet, once in your daily life.

Why then, when it comes to baseball players, are ballclubs so reluctant to get their mistakes out of sight?

The minute you mention releasing a high-priced ballplayer who has no trade value and no longer fits on the team, the reflexive response comes flying at you from every direction.

“They can’t do that,” the common response is. “They owe him almost $10 million.”

The Mets will pay Bobby Bonilla close to $10 million more whether he sits on Bobby Valentine’s bench, sits on his couch in Greenwich, Conn., or works as some American League team’s designated hitter.

That hurts the Mets in the wallet. So why let Bonilla hurt them twice, by taking up a roster spot that could be better used on a relief pitcher such as left-hander Rigo Beltran?

Releasing Bonilla would be the best solution for all parties involved.

As offensive as it sounds to those who have been around long enough to remember when 10 pitchers on a staff was the norm, the reality is that with the state of today’s pitching, some clubs are better constructed with 12 pitchers than 11. Clearly, the Mets are one of those teams.

The five men who make up the rotation at the moment – Al Leiter, Rick Reed, Orel Hershiser, Masato Yoshii and Jason Isringhausen – average less than six innings per start.

The Mets go to the bullpen more often than most teams and therefore need more relievers than most teams. An extra arm would ease the burden for Turk Wendell, who is on a pace to appear in 91 games. He’s too valuable to risk burning him out.

A 12th pitcher would be used more than Bonilla, who came to the Mets expecting to be used as the everyday right fielder. To expect his heart to be in a bench role is not being realistic. To use him daily in the outfield would be foolish because of the way Benny Agbayani has been hitting.

Valentine has been known to make unconventional rotations work, as evidenced last season when he used six starting pitchers in a rotation.

Rotating five outfielders for three spots was not a challenge even Valentine wanted to tackle. Understandably, he took the least productive outfielder out of the rotation – Bonilla – and now juggles four outfielders.

That reduces Bonilla, batting .167 with four home runs and 17 RBIs, to a bench player, backing up at first and in the outfield. He doesn’t run well and is not an adequate outfielder, which makes him less than ideally suited for a bench role even though he does switch hit.

Valentine said he told Bonilla the benching would last for six days. Why six days and what will happen then remains a mystery. If after the six days is up, the Mets are winning, the rotation is working and Wendell is still getting burned out, releasing Bonilla shouldn’t be as tough a sell on ownership.

The Dodgers were faced with a similar decision with Mel Rojas, the man for whom Bonilla was traded, and they ate his $4.5 million salary. They haven’t regretted the decision for a second.

There always is the chance Bonilla could go to the American League, get hot as a designated hitter and become a productive RBI man. Since Bonilla’s not going to get the at-bats here, and since there is no DH in the National League, the Mets can’t worry about him making them look bad.

Instead of looking at it as tearing up $10 million, look at it the way Blue Jay manager Jim Fregosi, one of the brighter, more experienced minds in the game, views it.

“If you don’t want to look at your mistake anymore, all it costs you is $200,000,” Fregosi said. “You’re going to call up a player making the minimum to replace him. In this case, that would be about $125,000 this year and $200,000 next year. That’s not expensive in today’s market.”

No it is not, but keeping Bonilla around in a role for which he is not suited could cost the Mets in many, many ways.